On Wed, May 09, 2012 at 11:20:07AM +0100, Ian Abbott wrote:> On 2012-05-09 00:55, H Hartley Sweeten wrote:> >On Tuesday, May 08, 2012 4:41 PM, H Hartley Sweeten wrote:> >>> >>The structs' comedi_insn, coomedi_insnlist, comedi_cmd,> >>comedi_chaninfo, and comedi_rangeinfo are all passed to> >>the kernel from user space using ioctl commands. They> >>are then copied to kernel space using copy_from_user()> >>before the data is passed to the drivers.> >>> >>The __user annotation should not be used with variables> >>inside the struct. This produces a lot of sparse warnings> >>like:> >>> >>warning: dereference of noderef expression> >>> >>Signed-off-by: H Hartley Sweeten<hsweeten@visionengravers.com>> >>Cc: Ian Abbott<abbotti@mev.co.uk>> >>Cc: Mori Hess<fmhess@users.sourceforge.net>> >>Cc: Greg Kroah-Hartman<gregkh@linuxfoundation.org>> >>> >>---> >>> >>Note: This patch exposes some new warnings about different> >>address space. These will be addressed.> >> >Please ignore this patch.> >> >It appears the annotations in the struct definitions are correct.> > Personally, I think you were on the mark with the patch. It's> better to avoid using __user in comedi.h so it can be used as-is in> user-space. All of the structures in comedi.h are used in user-space> (although Comedilib uses its own version of comedi.h without all the> typedef eliminations that have been done in "staging") and some of> them are also deep-copied into kernel-space objects of the same> type, where the pointers in the structs would no longer be> user-space pointers.

When the kernel exports .h files, stuff like this should work"automatically", so there is no need to not put __user markings.

So please, yes, continue to work to get this correct, it is veryessencial to ensure we don't mess stuff up.